Novel method for the synthesis of 4-thio and 4-seleno ethers of 2-pyrazolin-5-ones

ABSTRACT

Method for synthesizing 4-substituted thiol and 4-substituted seleno-2-pyrazolin-5-ones by reaction of an appropriate thiol or selenol compound with a 4,4-dihalo-2-pyrazolin-5-one.

The invention relates to a process for synthesizing thio and selenoether derivatives of 5-pyrazolones. In particular, this inventionrelates to an efficient one step process for obtaining 4-substitutedthio- and seleno ether derivatives of 2-pyrazolin-5-one compounds.

Some thio ether products of the above-described type are known in thecolor photographic art as DIR (Development-Inhibitor Releasing) or asBIR (Bleach Inhibitor Releasing) couplers. Such compounds have beenpreviously prepared, for instance, by reacting a halo substitutedcoupler with a cuprous aryl mercaptide or by condensation of aheterocyclyl sulfenyl halide with a 4-unsubstituted coupler moiety. Thelater process is used, for instance, in Column 38 (Coupler LXV) of U.S.Pat. 3,227,551. Known art processes, however, cannot always besuccessfully or efficiently used, due to a tendency to synthesizerelatively large amounts of dimers and other undesired by-products.Although substituted heterocyclyl sulfenyl halides can normally beprepared and readily condensed with 2-pyrazolin-5-ones, it is difficultand sometimes impossible to obtain a heterocyclyl sulfenyl halide havingone or more active hydrogen atoms. In this respect, the instant processis believed to represent the only practical method for obtaining certaincorresponding 4-substituted ethers. In any case, an efficient one-stepprocess is particularly useful in obtaining a DIR-type coupler such as a4-benzothiazolythio (or seleno)-substituted 5-pyrazolone.

It is an object of the present invention to efficiently and economicallyproduce 2-pyrazolin-5-one-thio or seleno-ether derivatives.

In addition, it is an object to obtain a class of 4-heterocyclylsubstituted magenta dye-forming couplers which cannot be readilyobtained by simple condensation reaction with a sulfenyl halide in theusual way.

These and other objects of the present invention are obtained byreacting together, preferably in an organic solvent system, a4,4-dihalo-2-pyrazolin-5-one such as a 4,4-dibromo-2-pyrazolin-5-onewith a thiol or selenol having the structure required to yield thedesired 4-substituted 2-pyrazolone-5-one; in particular, the thiol orselenol material should have the formula

    R.sup.3 --R.sup.4 H

wherein R⁴ is defined as --S-- or --Se--; and

R³ is defined as a heterocyclic group, an aryl group or an alkyl group.

This reaction is further conveniently described as follows: ##EQU1##WHEREIN COUP is defined as a ballasted or unballasted magentadye-forming 5-pyrazolone coupler group having the two bromine atoms andthe --R⁴ --R³ group, where appropriate, attached at the No. 4 positionon the pyrazolone ring; such groups being exemplified or otherwisesuggested, for instance, in U.S. Pat. Nos. 2,725,292, 2,772,161,2,895,826, 2,908,575, 2,920,961, 2,933,391, 2,983,608, 3,005,712,3,006,759, 3,062,653, 3,148,062, 3,152,896, 3,214,437, 3,227,554,3,253,924, 3,311,476, 3,419,391, 3,432,521, and 3,519,429;

R⁴ is defined as above; and

R³ is also generically defined as above, including

1. a heterocyclic group having 5-6 atoms in a heteronucleus containingat least one sulfur, nitrogen or oxygen atom; such group includes, forinstance, a benzoxazole group, a benzothiazole group, a benzimidazolegroup, an oxadiazole group, a thiadiazole group, a triazole group, aphenyl-substituted tetrazole group, a furanyl group, a benzofuranylgroup, an oxazolyl group, a pyranyl group, an oxazinyl group, or apyridyl group, including substituted heterocyclics such as alkyl, halo,hydroxyl, carboxyl, sulfo, amido, etc.;

2. an aryl group such as a phenyl group or a naphthyl group which isoptionally substituted by one or more nitro groups such as2-nitrophenyl, substituted by alkyl carbamyl group of 1-20 carbons suchas an eicosylcarbamyl phenyl group by an amino group including alkylamino phenyl, an alkoxy group of 1-20 carbons such as eicosyloxy,octadecyloxyphenyl, or methoxyphenyl; and

3. an alkyl group such as alkyl of 1-20 carbon (Ex. methyl, isopropyl,eicosyl);

groups (1)-(3) being exemplified, for instance, in U.S. Pat. Nos.3,227,554, 3,227,551, 3,148,062 3,615,056.

This process of the present invention is further conveniently expressedin accordance with the following equation: ##EQU2## wherein R¹ and R²can be the usual coupler ballasting or other groups such that

R¹ is defined

i. as hydrogen,

ii. as an aryl group inclusive of a phenyl or a naphthyl radicalexemplified by the following formula when R¹ is phenyl ##SPC1##

in which Y is individually defined as a halo group such as chloro orbromo, an alkyl group of 1-18 carbons such as methyl or octadecyl, as analkoxy group of 1-15 carbons, as a cyano group, as a nitro group orcombination thereof; and m is defined as 0-5, m values of 2-3 beingparticularly preferred;

iii. as an alkyl group including an alkyl group of 1-20 carbon atomssuch as methyl, isopropyl, and eicosyl;

iv. as an aryl carbonamido group inclusive of a phenyl carbonamido groupand optionally substituted by additional groups on the aryl ring, theadditional groups being exemplified by an alkylcarbonamido such as aphenoxyalkylcarbonamido including a di-(t)-amylphenoxyalkylcarbonamido-substituted-phenyl-carbonamido group;

v. as an amino group including substituted amines such as aryl amines(ex. phenylamino or a naphthyl amino group), the aryl ring of thearylamine being optionally further substituted by an alkylcarbonamidogroup inclusive of a phenoxy lower alkylcarbonamido group; and

vi. as a heterocyclic group having from 5-6 atoms in a heteronucleus andcontaining at least one oxygen, sulfur or nitrogen atom exemplified by a2-thiazolyl group, a 2-benzothiazolyl group a 2-benzoxazolyl group, a2-oxazolyl group, and a 2-benzimidozole group; and

R² is defined

i. as an alkyl group, including an alkyl group of 1-20 carbon atoms suchas methyl, isopropyl and eicosyl;

ii. as an arylamino group such as a phenylamino group, includingsubstituted arylamino group such as a halophenylamino, anitrophenylamino, a cyanophenylamino; and a

iii. as an alkylcarbonamido group, including substitutedalkylcarbonamido such as alkylphenoxy lower alkylcarbonamido exemplifiedby p-octadecylphenoxybutylcarbonamido;

iv. as an arylcarbonamido group such as a phenylcarbonamido group whichcan be optionally substituted on the aryl ring with an alkylcarbonamido,particularly a phenoxyalkylcarbon-amido group; and

v. as a heterocyclic group having a 5-6 membered heteronucleus such asdefined for R¹ and R³ ; and

R³ and R⁴ are the same as defined in formula I, above.

Additional suitable ballasting groups are disclosed, for instance, inU.S. Pat. No. 3,615,506.

The described synthesis is preferably effected under "mild reactionconditions" which are defined as preferably utilizing atmosphericpressure with a reaction temperature generally varying from about10°C.-70°C., preferably from 15°C.-50°C. and in the presence of an inertorganic reaction solvent. Such solvents in which both reactants can bedissolved at about 10°-70°C preferably to the extent of at least 1weight percent, include, for instance, acetonitrile and tetrahydrofuran.

It is also found for purposes of this invention that the term "reactiveproportions" covers molar ratios of 4,4 dibromo reactant-to-thiol orselenol reactant of from about 1:1 to about 1:5, a ratio of 1:3 beingpreferred.

The present processes can be carried out where at least one of thereactants is present in the reaction medium in an amount equal to atleast 0.001 moles, said reaction medium being an inert organic solventin which the reactants are dissolved. Timewise, the above-reaction mayvary from about one-half hr. to about 20 hours depending on thetemperature and/or pressure conditions utilized.

For purposes of further description of the reaction, both in terms ofreactants used and compounds obtained, reference is made to Equation IIand Table A below. ##SPC2##

The invention is further described, although not limited by thefollowing examples.

EXAMPLE I

To 1.2 Grams (2.05 × 10⁻ ³ mol) of1-(2,4,6-trichlorophenyl)-3-(2,4-dichloroanilino)4,4-dibromo-5-pyrazolone*dissolved in 80 ml acetonitrile were added 1.1 gm (6.2 × 10⁻ ³ mol) of1-phenyl-5-tetrazolylthiol dissolved in 20 ml of acetonitrile. Theyellow color of the 4,4-dibromo reactant is immediately discharged andthe mixture allowed to stand for 16 hours at 20°C., then concentratedand the resulting precipitated product recrystallized from acetonitrileand identified as Coupler No. 1 (Table A supra; M.P. 172°C.).

EXAMPLE II

To 7 Grams (.01 mol) of 1-[α-(2,4-di-(t)-amylphenoxy)butyramidophenyl]-3-N-pyrrolyl-4,4-dibromo-5-pyrazolone(**) dissolved in 200 mltetrahydrofuran were added with stirring 4.5 grams (0.03 mole) of2-benzimidazole thiol dissolved in 100 ml tetrahydrofuran; this reactionmixture was then stirred for 21/2 hours at 50°C. The solids werefiltered off and the filtrate dried. The 4-substituted product was thenrecrystallized from acetone and identified as Coupler No. 20 (Table Asupra; M.P. 185°-186°C.).

EXAMPLE III

To 16 Grams (.02 mole) of1-[4-α-(2,4-di-(t)-amylphenoxy)butyramidophenyl]-3-pyrrolyl-4,4-dibromo-5-pyrazolone(partly dissolved in tetrahydrofuran) were solwly added 14 grams (0.06mole) of 1-phenyltetrazolyl-5-selenol dissolved in tetrahydrofuran withagitation at 20°C. The reaction product was filtered to remove insolublenon-coupling material and the filtrate was then added to ligroin. Theresulting yellow solid was isolated and identified as Coupler No. 21(Table A supra; M.P. 134°-146°C.).

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

I claim:
 1. A process for obtaining a 4-thio- or a 4-seleno etherderivative of a 2-pyrazolin-5-one compound comprising reacting inreactive proportions in an inert organic reaction solvent and under mildreaction conditions a 4,4-dibromo-2-pyrazolin-5-one with a compound ofthe formula

    R.sup.3 --R.sup.4 H

wherein R⁴ is defined as --S-- or --Se--; and R³ is defined as aheterocyclic group having 5-6 atoms in a heteronucleus containing atleast one sulfur, nitrogen, or oxygen atom; an aryl group; or an alkylgroup, whereby said 4-thio- or 4-seleno-ether derivative of said2-pyrazolin-5-one compound is produced.
 2. A process of claim 1 whereinR⁴ is --S--.
 3. A process of claim 1 wherein R⁴ is --Se--.
 4. A processfor obtaining an ether compound of the formula ##EQU3## comprisingcontacting at a temperature of from about 10°C to about 70°C a reactiveamount of a dibromo compound of the formula

    COUP--(Br).sub.2

wherein Coup is defined as a ballasted or unballasted magentadye-forming 5-pyrazolone coupler group having the two bromine atoms andthe --R⁴ --R³ group attached to the No. 4 ring position; with a thiol orseleno compound of the formula

    R.sup.3 --R.sup.4 H

wherein R⁴ is defined as --S-- or --Se--; and R³ is defined as aheterocyclic group having 5-6 atoms in a heteronucleus containing atleast one sulfur, nitrogen, or oxygen atom, or an aryl group; thereaction of said dibromo compound with said thiol or selenol compoundbeing effected in an inert organic solvent; and thereafter recoveringsaid ether compound from the resulting reaction mixture.
 5. A process ofclaim 4 whereinR⁴ is --S--; and R³ is a benzoxazole group, abenzothiazole group, a benzimidazolyl group, an oxadiazole group, athiadiazole group, a triazole group, a phenyl-substituted tetrazolegroup, a furanyl group, a benzofuranyl group, an oxazolyl group, apyranyl group, an oxazinyl group or a pyridyl group.
 6. A process ofclaim 4 whereinR⁴ is --Se--; and R³ is a benzoxazole group, abenzothiazole group, a benzimidazolyl group, an oxadiazole group, athiadiazole group, a triazole group, a phenyl-substituted tetrazolegroup, a furanyl group, a benzofuranyl group, an oxazolyl group, apyranyl group, an oxazinyl group or a pyridyl group.
 7. A process ofclaim 5 wherein the reaction is effected in tetrahydrofuran at atemperature of about 15°C.-50°C.
 8. A process of claim 5 wherein thereaction is effected in acetonitrile at a temperature of about15°C.-50°C.
 9. A process of claim 6 wherein the reaction is effected intetrahydrofuran at a temperature of about 15°C.-50°C.
 10. A process ofclaim 6 wherein the reaction is effected in acetonitrile at atemperature of about 15°C.-50°C.
 11. A process for obtaining1-(2,4,6-trichlorophenyl)-3-(2,4-dichloroanilino)-4-(1-phenyltetrazolylthio)-5-pyrazolone comprising contacting (a)1-(2,4,6-trichlorophenyl)-3-(2,4-dichlorophenylanilino)-4,4-dibromo-5-pyrazolonewith (b) a compound of the formula ##EQU4## in a weight ration of (a) to(b) respectively of from about 1:1 to about 1:5 in an acetonitrilereaction solvent, and recovering the resulting thioether product.
 12. Aprocess as in claim 11 wherein the molar ratio of (a) to (b) is about1:3.
 13. A process for obtaining 1-[4-α-(2,4-di-(t)-amylphenoxybutyramidophenyl]-3-pyrrolyl-4-(2-benzimidazolyl thio)-5-pyrazolonecomprising contacting about .01 mole of the 4,4-dibromo precursor withabout 0.03 mole of 2-benzimidazole thiol dissolved in tetrahydrofuran asreaction solvent in a molar ratio of (a) to (b), respectively, of fromabout 1:1 to about 1:5 and recovering the resulting thioether product.14. A process as in claim 13, wherein the molar ratio of (a) to (b) isabout 1:3.
 15. A process for obtaining1-[4-α-(2,4-di-(t)-amylphenoxy)-butyramidophenyl]-3-pyrrolyl-4-(1-phenyl tetrazolyl seleno)-5-pyrazolonecomprising contacting about 0.06 mole of the 4,4-dibromo precursor withabout 0.02 mole of 1-phenyltetrazolyl-5-selenol in the presence oftetrahydrofuran reaction solvent at about 20°C., and recovering theresulting selenium ether product.
 16. A process as in claim 15 whereinthe molar ratio of (a) to (b) is about 1:3.